/* des.c */
/*
    This file is part of the ARM-Crypto-Lib.
    Copyright (C) 2006-2010  Daniel Otte (daniel.otte@rub.de)

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * \file     des.c
 * \author   Daniel Otte
 * \email    daniel.otte@rub.de
 * \date     2007-06-16
 * \brief    DES and EDE-DES implementation
 * \license   GPLv3 or later
 *
 */

#include "des.h"

const uint8_t sbox[256]  = {
    /* S-box 1 */
    0xE4, 0xD1, 0x2F, 0xB8, 0x3A, 0x6C, 0x59, 0x07,
    0x0F, 0x74, 0xE2, 0xD1, 0xA6, 0xCB, 0x95, 0x38,
    0x41, 0xE8, 0xD6, 0x2B, 0xFC, 0x97, 0x3A, 0x50,
    0xFC, 0x82, 0x49, 0x17, 0x5B, 0x3E, 0xA0, 0x6D,
    /* S-box 2 */
    0xF1, 0x8E, 0x6B, 0x34, 0x97, 0x2D, 0xC0, 0x5A,
    0x3D, 0x47, 0xF2, 0x8E, 0xC0, 0x1A, 0x69, 0xB5,
    0x0E, 0x7B, 0xA4, 0xD1, 0x58, 0xC6, 0x93, 0x2F,
    0xD8, 0xA1, 0x3F, 0x42, 0xB6, 0x7C, 0x05, 0xE9,
    /* S-box 3 */
    0xA0, 0x9E, 0x63, 0xF5, 0x1D, 0xC7, 0xB4, 0x28,
    0xD7, 0x09, 0x34, 0x6A, 0x28, 0x5E, 0xCB, 0xF1,
    0xD6, 0x49, 0x8F, 0x30, 0xB1, 0x2C, 0x5A, 0xE7,
    0x1A, 0xD0, 0x69, 0x87, 0x4F, 0xE3, 0xB5, 0x2C,
    /* S-box 4 */
    0x7D, 0xE3, 0x06, 0x9A, 0x12, 0x85, 0xBC, 0x4F,
    0xD8, 0xB5, 0x6F, 0x03, 0x47, 0x2C, 0x1A, 0xE9,
    0xA6, 0x90, 0xCB, 0x7D, 0xF1, 0x3E, 0x52, 0x84,
    0x3F, 0x06, 0xA1, 0xD8, 0x94, 0x5B, 0xC7, 0x2E,
    /* S-box 5 */
    0x2C, 0x41, 0x7A, 0xB6, 0x85, 0x3F, 0xD0, 0xE9,
    0xEB, 0x2C, 0x47, 0xD1, 0x50, 0xFA, 0x39, 0x86,
    0x42, 0x1B, 0xAD, 0x78, 0xF9, 0xC5, 0x63, 0x0E,
    0xB8, 0xC7, 0x1E, 0x2D, 0x6F, 0x09, 0xA4, 0x53,
    /* S-box 6 */
    0xC1, 0xAF, 0x92, 0x68, 0x0D, 0x34, 0xE7, 0x5B,
    0xAF, 0x42, 0x7C, 0x95, 0x61, 0xDE, 0x0B, 0x38,
    0x9E, 0xF5, 0x28, 0xC3, 0x70, 0x4A, 0x1D, 0xB6,
    0x43, 0x2C, 0x95, 0xFA, 0xBE, 0x17, 0x60, 0x8D,
    /* S-box 7 */
    0x4B, 0x2E, 0xF0, 0x8D, 0x3C, 0x97, 0x5A, 0x61,
    0xD0, 0xB7, 0x49, 0x1A, 0xE3, 0x5C, 0x2F, 0x86,
    0x14, 0xBD, 0xC3, 0x7E, 0xAF, 0x68, 0x05, 0x92,
    0x6B, 0xD8, 0x14, 0xA7, 0x95, 0x0F, 0xE2, 0x3C,
    /* S-box 8 */
    0xD2, 0x84, 0x6F, 0xB1, 0xA9, 0x3E, 0x50, 0xC7,
    0x1F, 0xD8, 0xA3, 0x74, 0xC5, 0x6B, 0x0E, 0x92,
    0x7B, 0x41, 0x9C, 0xE2, 0x06, 0xAD, 0xF3, 0x58,
    0x21, 0xE7, 0x4A, 0x8D, 0xFC, 0x90, 0x35, 0x6B
};

const uint8_t e_permtab[] = {
    4,  6,                     /* 4 bytes in 6 bytes out*/
    32,  1,  2,  3,  4,  5,
    4,  5,  6,  7,  8,  9,
    8,  9, 10, 11, 12, 13,
    12, 13, 14, 15, 16, 17,
    16, 17, 18, 19, 20, 21,
    20, 21, 22, 23, 24, 25,
    24, 25, 26, 27, 28, 29,
    28, 29, 30, 31, 32,  1
};

const uint8_t p_permtab[] = {
    4,  4,                     /* 32 bit -> 32 bit */
    16,  7, 20, 21,
    29, 12, 28, 17,
    1, 15, 23, 26,
    5, 18, 31, 10,
    2,  8, 24, 14,
    32, 27,  3,  9,
    19, 13, 30,  6,
    22, 11,  4, 25
};

const uint8_t ip_permtab[] = {
    8,  8,                     /* 64 bit -> 64 bit */
    58, 50, 42, 34, 26, 18, 10, 2,
    60, 52, 44, 36, 28, 20, 12, 4,
    62, 54, 46, 38, 30, 22, 14, 6,
    64, 56, 48, 40, 32, 24, 16, 8,
    57, 49, 41, 33, 25, 17,  9, 1,
    59, 51, 43, 35, 27, 19, 11, 3,
    61, 53, 45, 37, 29, 21, 13, 5,
    63, 55, 47, 39, 31, 23, 15, 7
};

const uint8_t inv_ip_permtab[] = {
    8, 8,                      /* 64 bit -> 64 bit */
    40, 8, 48, 16, 56, 24, 64, 32,
    39, 7, 47, 15, 55, 23, 63, 31,
    38, 6, 46, 14, 54, 22, 62, 30,
    37, 5, 45, 13, 53, 21, 61, 29,
    36, 4, 44, 12, 52, 20, 60, 28,
    35, 3, 43, 11, 51, 19, 59, 27,
    34, 2, 42, 10, 50, 18, 58, 26,
    33, 1, 41,  9, 49, 17, 57, 25
};

const uint8_t pc1_permtab[] = {
    8,  7,                     /* 64 bit -> 56 bit*/
    57, 49, 41, 33, 25, 17,  9,
    1, 58, 50, 42, 34, 26, 18,
    10,  2, 59, 51, 43, 35, 27,
    19, 11,  3, 60, 52, 44, 36,
    63, 55, 47, 39, 31, 23, 15,
    7, 62, 54, 46, 38, 30, 22,
    14,  6, 61, 53, 45, 37, 29,
    21, 13,  5, 28, 20, 12,  4
};

const uint8_t pc2_permtab[] = {
    7,  6,                     /* 56 bit -> 48 bit */
    14, 17, 11, 24,  1,  5,
    3, 28, 15,  6, 21, 10,
    23, 19, 12,  4, 26,  8,
    16,  7, 27, 20, 13,  2,
    41, 52, 31, 37, 47, 55,
    30, 40, 51, 45, 33, 48,
    44, 49, 39, 56, 34, 53,
    46, 42, 50, 36, 29, 32
};

const uint8_t splitin6bitword_permtab[] = {
    8,  8,                     /* 64 bit -> 64 bit */
    64, 64,  1,  6,  2,  3,  4,  5,
    64, 64,  7, 12,  8,  9, 10, 11,
    64, 64, 13, 18, 14, 15, 16, 17,
    64, 64, 19, 24, 20, 21, 22, 23,
    64, 64, 25, 30, 26, 27, 28, 29,
    64, 64, 31, 36, 32, 33, 34, 35,
    64, 64, 37, 42, 38, 39, 40, 41,
    64, 64, 43, 48, 44, 45, 46, 47
};

const uint8_t shiftkey_permtab[] = {
    7,  7,                     /* 56 bit -> 56 bit */
    2,  3,  4,  5,  6,  7,  8,  9,
    10, 11, 12, 13, 14, 15, 16, 17,
    18, 19, 20, 21, 22, 23, 24, 25,
    26, 27, 28,  1,
    30, 31, 32, 33, 34, 35, 36, 37,
    38, 39, 40, 41, 42, 43, 44, 45,
    46, 47, 48, 49, 50, 51, 52, 53,
    54, 55, 56, 29
};

const uint8_t shiftkeyinv_permtab[] = {
    7,  7,
    28,  1,  2,  3,  4,  5,  6,  7,
    8,  9, 10, 11, 12, 13, 14, 15,
    16, 17, 18, 19, 20, 21, 22, 23,
    24, 25, 26, 27,
    56, 29, 30, 31, 32, 33, 34, 35,
    36, 37, 38, 39, 40, 41, 42, 43,
    44, 45, 46, 47, 48, 49, 50, 51,
    52, 53, 54, 55
};

/*
1 0
1 0
2 1
2 1
2 1
2 1
2 1
2 1
----
1 0
2 1
2 1
2 1
2 1
2 1
2 1
1 0
*/
#define ROTTABLE      0x7EFC
#define ROTTABLE_INV  0x3F7E
/******************************************************************************/

void permute(const uint8_t *ptable, const uint8_t *in, uint8_t *out) {
    uint8_t ob; /* in-bytes and out-bytes */
    uint8_t byte, bit; /* counter for bit and byte */
    ob = ptable[1];
    ptable = &(ptable[2]);
    for (byte = 0; byte < ob; ++byte) {
        uint8_t t = 0;
        for (bit = 0; bit < 8; ++bit) {
            uint8_t x = *ptable++ - 1;
            t <<= 1;
            if ((in[x / 8]) & (0x80 >> (x % 8))) {
                t |= 0x01;
            }
        }
        out[byte] = t;
    }
}

/******************************************************************************/

void changeendian32(uint32_t *a) {
    *a = (*a & 0x000000FF) << 24 |
         (*a & 0x0000FF00) <<  8 |
         (*a & 0x00FF0000) >>  8 |
         (*a & 0xFF000000) >> 24;
}

/******************************************************************************/
static inline
void shiftkey(uint8_t *key) {
    uint8_t k[7];
    memcpy(k, key, 7);
    permute((uint8_t *)shiftkey_permtab, k, key);
}

/******************************************************************************/
static inline
void shiftkey_inv(uint8_t *key) {
    uint8_t k[7];
    memcpy(k, key, 7);
    permute((uint8_t *)shiftkeyinv_permtab, k, key);

}

/******************************************************************************/
static inline
uint64_t splitin6bitwords(uint64_t a) {
    uint64_t ret = 0;
    a &= 0x0000ffffffffffffLL;
    permute((uint8_t *)splitin6bitword_permtab, (uint8_t *)&a, (uint8_t *)&ret);
    return ret;
}

/******************************************************************************/

static inline
uint8_t substitute(uint8_t a, uint8_t *sbp) {
    uint8_t x;
    x = sbp[a >> 1];
    x = (a & 1) ? x & 0x0F : x >> 4;
    return x;

}

/******************************************************************************/

uint32_t des_f(uint32_t r, uint8_t *kr) {
    uint8_t i;
    uint32_t t = 0, ret;
    uint64_t data;
    uint8_t *sbp; /* sboxpointer */
    permute((uint8_t *)e_permtab, (uint8_t *)&r, (uint8_t *)&data);
    for (i = 0; i < 6; ++i)
        ((uint8_t *)&data)[i] ^= kr[i];

    /* Sbox substitution */
    data = splitin6bitwords(data);
    sbp = (uint8_t *)sbox;
    for (i = 0; i < 8; ++i) {
        uint8_t x;
        x = substitute(((uint8_t *)&data)[i], sbp);
        t <<= 4;
        t |= x;
        sbp += 32;
    }
    changeendian32(&t);

    permute((uint8_t *)p_permtab, (uint8_t *)&t, (uint8_t *)&ret);

    return ret;
}

/******************************************************************************/

typedef struct {
    union {
        uint8_t  v8[8];
        uint32_t v32[2];
    } d;
} data_t;
#define R (data.d.v32[1])
#define L (data.d.v32[0])

void des_enc(void *out, const void *in, const void *key) {

    uint8_t kr[6], k[7];
    uint8_t i;
    data_t data;

    permute((uint8_t *)ip_permtab, (uint8_t *)in, data.d.v8);
    permute((uint8_t *)pc1_permtab, (const uint8_t *)key, k);

    for (i = 0; i < 8; ++i) {
        shiftkey(k);
        if (ROTTABLE & ((1 << ((i << 1) + 0))))
            shiftkey(k);
        permute((uint8_t *)pc2_permtab, k, kr);
        L ^= des_f(R, kr);

        shiftkey(k);
        if (ROTTABLE & ((1 << ((i << 1) + 1))))
            shiftkey(k);
        permute((uint8_t *)pc2_permtab, k, kr);
        R ^= des_f(L, kr);

    }
    /* L <-> R*/
    R ^= L;
    L ^= R;
    R ^= L;

    permute((uint8_t *)inv_ip_permtab, data.d.v8, (uint8_t *)out);
}

/******************************************************************************/

void des_dec(void *out, const void *in, const uint8_t *key) {

    uint8_t kr[6], k[7];
    int8_t i;
    data_t data;

    permute((uint8_t *)ip_permtab, (uint8_t *)in, data.d.v8);
    permute((uint8_t *)pc1_permtab, (const uint8_t *)key, k);
    for (i = 7; i >= 0; --i) {

        permute((uint8_t *)pc2_permtab, k, kr);
        L ^= des_f(R, kr);
        shiftkey_inv(k);
        if (ROTTABLE & ((1 << ((i << 1) + 1)))) {
            shiftkey_inv(k);
        }

        permute((uint8_t *)pc2_permtab, k, kr);
        R ^= des_f(L, kr);
        shiftkey_inv(k);
        if (ROTTABLE & ((1 << ((i << 1) + 0)))) {
            shiftkey_inv(k);
        }

    }
    /* L <-> R*/
    R ^= L;
    L ^= R;
    R ^= L;

    permute((uint8_t *)inv_ip_permtab, data.d.v8, (uint8_t *)out);
}

/******************************************************************************/

void tdes_enc(void *out, void *in, const void *key) {
    des_enc(out,  in, (uint8_t *)key + 0);
    des_dec(out, out, (uint8_t *)key + 8);
    des_enc(out, out, (uint8_t *)key + 16);
}

/******************************************************************************/

void tdes_dec(void *out, void *in, const uint8_t *key) {
    des_dec(out,  in, (uint8_t *)key + 16);
    des_enc(out, out, (uint8_t *)key + 8);
    des_dec(out, out, (uint8_t *)key + 0);
}

void tdes_2key_enc(void *out, const void *in, size_t length, const void *key, unsigned char iv[8]) {

    if (length % 8) return;

    uint8_t i;
    uint8_t *tin = (uint8_t *) in;
    uint8_t *tout = (uint8_t *) out;

    while (length > 0) {
        for (i = 0; i < 8; i++)
            tout[i] = (unsigned char)(tin[i] ^ iv[i]);

        des_enc(tout,  tin, (uint8_t *)key + 0);
        des_dec(tout, tout, (uint8_t *)key + 8);
        des_enc(tout, tout, (uint8_t *)key + 0);

        memcpy(iv, tout, 8);

        tin  += 8;
        tout += 8;
        length -= 8;
    }
}

void tdes_2key_dec(void *out, const void *in, size_t length, const void *key, unsigned char iv[8]) {

    if (length % 8) return;

    uint8_t i;
    unsigned char temp[8];
    uint8_t *tin = (uint8_t *) in;
    uint8_t *tout = (uint8_t *) out;

    while (length > 0) {
        memcpy(temp, tin, 8);

        des_dec(tout,  tin, (uint8_t *)key + 0);
        des_enc(tout, tout, (uint8_t *)key + 8);
        des_dec(tout, tout, (uint8_t *)key + 0);

        for (i = 0; i < 8; i++)
            tout[i] = (unsigned char)(tout[i] ^ iv[i]);

        memcpy(iv, temp, 8);

        tin  += 8;
        tout += 8;
        length -= 8;
    }
}


/******************************************************************************/


